A gateway drug to the wonderful world of Emacs and Spacemacs for Clojure users.
- Clojure cheat sheet: a summary of all the essentials. Using Clojure inside Fiji. Go to Plugins › Scripting › Clojure Interpreter. The prompt accepts any clojure code. See also Fiji's Script Editor. See Scripting Help for details on keybindings and how to use the interpreter. ^ Ctrl+) will add all necessary ending parenthesis.
- There is a test suite in clojure-cheatsheet-tests.el that checks that every symbol defined in the cheatsheet is valid, and that every symbol defined by Clojure is in the sheet (with a few explicit exceptions). To run the test suite: Clone the project. Open clojure-cheatsheet-tests.el and eval the whole file.
- Count get subs compare (clojure.string/) join escape split split-lines replace replace-first reverse (1.5) re-quote-replacement (java.lang.String).indexOf.lastIndexOf Regex #' pattern ' re-find re-seq re-matches re-pattern re-matcher re-groups (clojure.string/) replace replace-first (1.5) re-quote-replacement.
None of the following config is meant to be permanent, although it could be used as the basis of a personal emacs configuration. It’s meant as a basic setup so non-emacs users can try out emacs as simply and quickly as possible.
First some terminology
Installing Clojure Specific Plugins
Count get subs compare (clojure.string/) join escape split split-lines replace replace-first reverse (1.5) re-quote-replacement (java.lang.String).indexOf.lastIndexOf Regex #' pattern ' re-find re-seq re-matches re-pattern re-matcher re-groups (clojure.string/) replace replace-first (1.5) re-quote-replacement.
Clojure mode comes by default, but there are some other things that help. Most importantly, Cider. This is available from the melpa archive and the first step is to add that. There are several ways, but as emacs lisp is very closely related to Clojure and we can run lisp commands directly from emacs, the easiest way is to use that method. To do this call up the lisp interpreter by either of these:
M-x eval-expression
M-S-;
Then enter the command you want to run. Ie:
Fetching the list of packages can take a while depending on network connection. Best to check it, if the last command fails, with:
You can now start a repl by navigating to a Clojure project root directory and running the following command:
A Minimal Set of Commands. Just enough to get going…
Window Controls
Emacs by default will split windows so you can see multiple buffers at once. This behaviour can be changed, but to start with learning these basics:
Opening Files
Note that sometimes this is bound to C-x d. The one you need is the one that DOESN’T say (brief) in the minibuffer. Try them both. The (brief) version is not useful.
<return> open file at point
Navigation
(arrow keys also work as expected. Ctrl-arrow gives bigger movements)
Cut and Paste
The emacs model for cut and paste predates the generally used C-c C-v convention. It is possible to modify this, but better to understand the emacs default behaviour first. A region is the text between the cursor and the “mark”. This can be cut and stored in the cut buffer and “yanked” back again.
Help
Emacs can provide all sorts of help, even straight out of the box. Here are some shortcuts:
Other Essentials
That should be enough to actually get around and edit files and run Clojure functions either in the repl or directly from the files. Before continuing it’s worth adding a few helpful packages. These often have ready made keybindings, but not always. Most people will keep the bindings we have seen so far, but this is not possible for every combination of all possible packages. Commands can always be run using M-x and the command name though. Emacs will tell you if the command is already bound to a key and you can use that binding or re-bind it as you see fit.
Cider
Cider had a wealth of commands, none of which are bound to keys by default. At the very least it would be good to bind cider-jack-in to something. I would recommend C-c C-j but for now, just run them from M-x.
Non-essential, but useful, additions
Paredit Mode
Makes life easier by strictly matching paren pairs. Not the only option, there are other similar packages worth investigating too. Install it with package-install and enable it for all Clojure files with these lisp commands:
(package-install ‘paredit)
(add-hook 'clojure-mode-hook 'enable-paredit-mode)
Useful paredit commands:
Which-key
Makes finding half-remembered commands a whole lot easier
Now if you start to type a keybinding, all the options will appear in the mini-buffer. Try it by typing C-x. There are many useful commands starting with C-x.
Ivy
Improves searching for M-x commands.
(package-install ‘ivy)
(setq ivy-use-selectable-prompt t)
(ivy-mode 1)
Swiper
Makes searching in a file much easier
(package-install ‘swiper)
(global-set-key 'C-s' 'swiper)
Smex and Counsel
Smex in counsel-mode gives a nice command history for M-x commands. Also, counsel provides many more overlays to built-in functions that are well worth exploring.
(package-install ‘smex)
(smex-install)
(package-install ‘counsel)
(counsel-mode 1)
Problems
Lein not found?
You may need to add an entry to exec-path, which is what emacs uses to find executables for external commands. Some versions of emacs set this from $PATH, others don’t so if you have lein installed in your home directory you may need to add that to emacs’ exec-path.
(add-to-list 'exec-path '/Users/<me>/bin')
Stop the bell ringing
Clojure Cheat Sheet Download
(setq ring-bell-function 'ignore)
Broken config file
Sometimes problems occur when editing emacs init files that stop it from booting properly. Moving/renaming it and starting with bare emacs again to fix the problem is one way to do it. I prefer this:
vi ~/emacs.d/init.el
What next?
All the preceding info is arranged to help try out emacs. Although emacs will remember certain things like the packages installed, it won’t automatically remember all the settings applied. Any lisp code that has been run using M-S-; can also be added to a startup file so it gets applied every time. The best starting place is ~/.emacs.d/init.el. This is the whole of the above setup in one place. This can be pasted into your init.el file:
(require 'package)
(package-initialize)
(add-to-list 'package-archives '('melpa' . 'http://melpa.org/packages/') t)
(package-install 'cider)
(package-install 'paredit)
(paredit-mode)
(add-hook 'clojure-mode-hook 'enable-paredit-mode)
(package-install 'which-key)
(which-key-mode 1)
(package-install 'ivy)
(setq ivy-use-selectable-prompt t)
(ivy-mode 1)
(package-install 'swiper)
(global-set-key 'C-s' 'swiper)
(package-install 'smex)
(smex-initialize)
(package-install 'counsel)
(counsel-mode 1)
You may prefer to only keep certain parts. There are also many good emacs starter packs, although there is a lot to be said for starting from scratch and only adding things you will actually use. Browse the available packages with this command:
C-x package-list-packages
Some other useful ones worth trying are:
- magit
- git-gutter
- paradox
- rainbow-parens
- aggressive-indent-mode
- evil
- flycheck
- google-translate
- tetris
- …
Cljs
Spacemacs
Spacemacs is a self contained emacs setup. It has a curated set of packages and bindings and some might prefer this to setting up and tweaking their own system. It is also tailored to be easy for vi users to use, although this can also be done in regular emacs by installing evil-mode. Underneath it’s still just emacs so the basics are the same either way. Emacs must be installed and run as normal. Spacemacs is not a separate application.
Clojure Cheat Sheet Pdf
A lot of the niceties detailed above are already included in spacemacs but installing cider is slightly different.
To setup spacemacs from scratch first remove all traces of emacs config files then install the spacemacs config to ~/.emacs.d:
cd ~
mv .emacs.d .emacs.d.bak
mv .emacs .emacs.bak
git clone https://github.com/syl20bnr/spacemacs ~/.emacs.d
Try running emacs and let it install all the necessary packages. This may take a while and may also require exiting emacs and restarting. When it comes up clean, then cider can be added. Do this by editing ~/.spacemacs and adding clojure to the existing dotspacemacs-configuration-layers list and restarting. At this point most of the above information will apply.
You can download a short printable version of the cheatsheets here: